How To Get Ubuntu, Debian, Kali Release Version?

I have take new job and I have a lot of new Ubuntu servers to manage. There is no inventory about the Ubuntu servers. I only know that they are Ubuntu. Is there a way to get Ubuntu version of this servers?

Linux Standarts Base aka LSB defines starndarts for different Linux distributions. Ubuntu comply with LSB. In LSB complied distributions should store their release versions at /etc/lsb-release so we can simple Ubuntu version from there.